Single speed pumps are your traditional pool pump and have been in use for decades. Once turned on, it runs at a constant speed. These pool pumps are the least expensive to purchase, however they are extremely noisy and inefficient.
A Two-Speed pool pump is a variation of the single speed pool pump, in that they both use what’s known as an induction style motor. The difference is that a two-speed pool pump has a low speed option, which is far more efficient than running the pump on high speed all the time.
Variable speed pool pumps are an entirely different animal. Unlike the inefficient induction motors used in single and two-speed pool pumps, variable speed pool pumps utilize what’s known as a permanent magnet motor. This is the same type of motor used in electric cars, and they allow the user to “dial in” the exact flow rate they need for their pool. Allowing them to capitalize on the golden rule of pool circulation: slower is better. The idea is that by reducing the flow rate of water, there is less friction, which makes the entire pool pump system more efficient.